1. Field of the Invention
The present invention relates to radio frequency identification (“RFID”) technology. More particularly, the present invention relates to networks that include RFID devices.
2. Description of the Related Art
“Smart labels,” generally implemented by RFID tags, have been developed in an effort to address the shortcomings of bar codes and add greater functionality. RFID tags have been used to keep track of items such as airline baggage, items of clothing in a retail environment, cows and highway tolls. As shown in FIG. 1, an RFID tag 100 includes microprocessor 105 and antenna 110. In this example, RFID tag 100 is powered by a magnetic field 145 generated by an RFID reader 125. The tag's antenna 110 picks up the magnetic signal 145. RFID tag 100 modulates the signal 145 according to information coded in the tag and transmits the modulated signal 155 to the RFID reader 125.
RFID tags use the Electronic Product Code (“EPC” or “ePC”) format for encoding information. An EPC code includes a variable number of bits of information (common formats are 64, 96 and 128 bits), which allows for identification of individual products as well as associated information. As shown in FIG. 1, EPC 120 includes header 130, EPC Manager field 140, Object class field 150 and serial number field 160. EPC Manager field 140 contains manufacturer information. Object class field 150 includes a product's stock-keeping unit (“SKU”) number. Serial number field 160 is normally a 40-bit field that can uniquely identify the specific instance of an individual product i.e., not just a make or model, but also down to a specific “serial number” of a make and model.
In theory, RFID tags and associated RFID devices (such as RFID readers and printers) could form part of a network for tracking a product (or a group of products) and its history. However, various difficulties have prevented this theory from being realized. One problem that has required considerable time and energy from RF engineers is the development of lower-cost RFID tags with acceptable performance levels. Inductively-coupled RFID tags have acceptable performance levels. These tags include a microprocessor, a metal coil and glass or polymer encapsulating material. Unfortunately, the materials used in inductively-coupled RFID tags make them too expensive for widespread use: a passive button tag costs approximately $1 and a battery-powered read/write tag may cost $100 or more.
Capacitively-coupled RFID tags use conductive ink instead of the metal coil used in inductive RFID tags. The ink is printed on a paper label by an RFID printer, creating a lower-cost, disposable RFID tag. However, conventional capacitively-coupled RFID tags have a very limited range. In recent years, RF engineers have been striving to extend the range of capacitively-coupled RFID tags beyond approximately one centimeter.
In part because of the significant efforts that have been expended in solving the foregoing problems, prior art systems and methods for networking RFID devices are rather primitive. RFID devices have only recently been deployed with standard network interfaces such as Ethernet. Device provisioning for prior art RFID networks is not automatic, but instead requires a time-consuming process for configuring each individual device.
Conventional RFID devices also have a small amount of available memory. A typical RFID device may have approximately 0.5 Mb of flash memory and a total of 1 Mb of overall memory. The small memories of RFID devices place restrictions on the range of possible solutions to the problems noted herein. In addition, an RFID device typically uses a proprietary operating system, e.g., of the manufacturer of the microprocessor(s) used in the RFID device.
Prototype RFID network deployments to date require large human/support intervention to be implemented. RFID devices are being deployed with “static” knowledge of where the device was deployed at original time of deployment. RFID devices are statically configured to a single RFID middleware server (formerly known as a “Savant”). Current implementations require each RFID middleware server to contact RFID devices that have been manually associated with that server. Moreover, such networks do not provide for RFID middleware server redundancy.
For these and other reasons, prior art devices and methods are not suitable for the large-scale deployment of RFID devices, middleware servers and other devices in a network. Methods and devices are needed for migrating first generation RFID systems to scalable RFID networks.